Which statement best explains the risk associated with excessive interpass heating?

• A. It can promote cracking
• B. It reduces cracking risk
• C. It has no effect on cracking
• D. It only affects corrosion

Answer: (A)

Excessive interpass heating increases the risk of cracking by altering the weld and heat‑affected zone (HAZ) microstructure and by raising residual stresses. When each pass is heated too hot, previously laid weld metal and surrounding material can reheat beyond optimal cooling ranges, causing coarser grains or re-austenitization in steels. This reduces toughness and makes the metal more susceptible to crack initiation and propagation, especially if hydrogen is present or the metal has high hardenability. The extra heat also adds residual stresses from repeated heating and nonuniform cooling, which further drives crack growth. So, higher interpass temperatures create conditions that favor cracking, which is why excessive interpass heating is a real safety and integrity concern.